One of the guys I work with was talking about this the other day. He told me if you don't have a park ID, you can buy a ticket to get in for $2.
Even people not playing, (i.e. a spouse, just wanting to watch) have to show a park ID or buy a $2 ticket.
Also, there are specific time periods set up for adult play and periods for kids to play. If I remember right Sundays the courts can be reserved. I do not remember how this worked, guess I need to learn to listen better.